Which of the following features distinguishes RNA from DNA? a) DNA has only purine bases b) RNA has a pentose sugar while DNA utilizes a hexose sugar c) Unlike RNA, DNA uses a phosphodiester backbone d) RNA has only pyrimidine bases e) None of the above

Which of the following traits exemplify plasmid DNA? A) It often carries genes beneficial to its bacterial host. B) It replicates independently of the genomic DNA. C) It is always larger than the genomic DNA. D) Both A and B, above E) Both B and C, above

D) Both A and B, above

DNA consists of repeating units of nucleotides. Which is NOT a component of a nucleotide? a) a deoxyribose sugar b) a ribose sugar c) phosphate d) purine or pyrimidine nitrogen-containing bases e) DNA contains all of the above.

b) a ribose sugar

Which of the following statements is not true concerning RNA and DNA? a) RNA is more stable than DNA b) DNA is transcribed into RNA which is translated into protein c) DNA is permanent in a cell, RNA is temporary d) The sugar portion of RNA and DNA are different

a) RNA is more stable than DNA

Write the anticodon, with correct polarity, of all tRNAs that will bind to the mRNA codon 5' UCG 3', considering wobble-base pairing rules

3' AGC 5' 3' AGA 5' 3' AGG 5' 3' AGU 5'

This molecule is synthesized using nucleotides containing the bases adenine, guanine, cytosine, and uracil: RNA only

RNA only

A bacterial protein is encoded by the following mRNA sequence: AUGGUGCUCAUGCCCTAA.… The second methionine codon (AUG) in this mRNA sequence will serve as the initiation codon. encode N-formylmethionine. encode methionine that will eventually be removed. encode unformylated methionine.

encode unformylated methionine.

What chemical group is found at the 5' end of a DNA molecule? sulfate group hydroxyl group phosphate group nitrogenous base carboxyl group dideoxy group

phosphate group

In DNA replication, the lagging strand is a) the part of the DNA which is just about to be unwound. b) the portion of the helix that is not anti-parallel with its paired strand. c) the portion of the DNA that has been fully replicated. d) the strand which must be replicated in a direction toward the replication fork. e) the strand which must be replicated in a direction away from the replication fork.

e) the strand which must be replicated in a direction away from the replication fork.

Which of the following statements about the genetic code are TRUE? a) Most amino acids are encoded by more than one codon b) The code is ambiguous but not redundant c) There is only one codon for each amino acid d) Two consecutive bases specify an amino acid e) None of the above

a) Most amino acids are encoded by more than one codon

Briefly discuss the evidence for the semi-conservative replication of DNA

Experiments by Matthew Meselson and Frank Stahl allowed E. coli to be labeled with 15N and 14N and then followed the density of the daughter cells using cesium chloride gradient centrifugation. They predicted that parental DNA molecules of one density which were allowed to replicate in another medium of a different density will show daughter DNA molecules of intermediate density because half will be old DNA and the other half will be new DNA. Their results proved that indeed half was old and other half was new indicating DNA of intermediate density.

Which of the following DNA double helices would be more difficult to separate into single-stranded molecules by treatment with heat (which breaks hydrogen bonds)? Indicate the reason (or reasons) for your choice. A: GTATTAGAACATCTC CATAATCTTGTAGAG B: TGAGCGTTCCAGCAG ACTCGCAAGGTCGTC DNA molecule A DNA molecule B DNA molecule A has a lower A-T content DNA molecule B has a higher G-C content DNA molecule A has a higher G-C content. DNA molecule A has a higher A-T content

This term describes the sequence of nucleotides which direct the formation of a new nucleic acid strand.

Which of the following statements best describes the messenger RNA? a) mRNA is synthesized by ribosomes in the endoplasmatic reticulum b) mRNA is the only type of RNA that carries DNA's protein building instructions c) mRNA consists of an anti-codon and an amino acid d) genetic information is permanently stored in mRNA e) mRNA molecules have a double-helix structure

b) mRNA is the only type of RNA that carries DNA's protein building instructions

What is a gene? a) A sequence of amino acids that catalyze a reaction b) A sequence of RNA that regulates expression c) A sequence of DNA that encodes a protein d) A sequence of DNA that tells polymerase where to begin transcription

c) A sequence of DNA that encodes a protein

Which is a characteristic of DNA sequences at the telomeres? a) all of the above b) The consist of repeated sequences c) One strand protrudes beyond the other, creating some single-stranded DNA at the end. d) They consist of cytosine and adenine nucleotides

a) all of the above

This method of replication preserves the covalent links on one strand of DNA but allows permanent separation of the "parental" double helix to form two templates.

semiconservative

DNA primase:

RNA primer synthesis

DNA gyrase:

supercoil removal

Short “bursts” of DNA synthesis that establish the lagging strand are called these.

okazaki fragments

The TATA-binding protein (TBP) binds to the TATA box sequence in eukaryotic promoters. What is its function in transcriptional initiation? It blocks access of RNA polymerase to the promoter, until removed by general transcription factors. It is the subunit of prokaryotic RNA polymerase that is required to recognize promoters. It modifies histones so that nucleosomes can be removed from DNA for transcription. It bends and partly unwinds DNA at a promoter.

It bends and partly unwinds DNA at a promoter.

Which of the following best describes the addition of nucleotides to a growing DNA chain? Question options: a) A nucleoside diphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate. b) A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate. c) A nucleoside diphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate. d) A nucleoside triphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate.

b) A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate.

An mRNA has the stop codon 5'UAA3'. What tRNA anticodon will bind to it? 5'ATT3' 5'AUC3" 5" ACU3' none

none

The packaging of DNA into a confined space is what level of DNA structure? a) primary b) quaternary c) tertiary d) secondary

Which of the following statements about a mammalian messenger RNA are FALSE? a) It is synthesized in the nucleus. b) It is translated in the cytoplasm. c) It usually contains a cap at the 5' end. d) It is usually much smaller than the initial transcript (that is copied directly from the gene). e) None of the above.

e) None of the above.

What secondary structures are formed when single-stranded DNA or RNA is inverted and complementary? a) hairpin b) double helix c) B-DNA d) Z-DNA

In what cellular compartment are introns removed from pre-mRNA to make mature mRNA? Cytoplasm Endoplasmic Reticulum Nucleus Mitochondia Golgi apparatus

Nucleus

This new strand of DNA has its 3' end oriented in the same direction as the replication fork travels.

leading

Rolling-circle replication:

unidirectional replication

Which of the following are role(s) of the 5’ cap? The cap helps the RNA polymerase find the promoter and initiate transcription. The cap plays a role in the removal of introns. The cap acts as a binding site for the ribosome. The cap protects the RNA from degradation. none of the above

The cap plays a role in the removal of introns. The cap acts as a binding site for the ribosome. The cap protects the RNA from degradation.

RNA polymerase must bind to a region of DNA called a promoter in order to begin transcription.

promoter

Eukaryotes have two of these per chromosome; prokaryotes have none. Telomeres.

Telomeres.

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? a) DNA contains purines, whereas protein includes pyrimidines. b) DNA contains sulfur, whereas protein does not. c) DNA contains phosphorus, but protein does not d) DNA contains nitrogen, whereas protein does not.

c) DNA contains phosphorus, but protein does not

What would Hershey and Chase have concluded if phage ghosts contained 32P label but were absent from infected E. coli? Furthermore, they found 35S lacking in the ghosts and present in the infected E. coli. a) that protein and DNA together made up the genetic material b) that DNA was the genetic material in phage c) that protein was the genetic material in phage d) that somehow the radioactivity prevented DNA from getting into E. coli

c) that protein was the genetic material in phage

Heterochromatin is characterized by all of the following, EXCEPT that it a) is present at centromeres and telomeres. b) contains genes that require high levels of transcription. c) is present on most of the Y chromosome. d) is present all over the inactive X chromosomes in mammals. e) remains highly condensed throughout the cell cycle.

b) contains genes that require high levels of transcription

In each round of the elongation cycle of protein synthesis, a new _______ binds to the codon in the _______ site, then the peptide is transferred from the tRNA in the _______ site to the new aminoacyl-tRNA, and finally the entire _______ moves along the mRNA in a 5' to 3' direction. a) tRNA; P; A; peptidyl-tRNA b) synthetase; P; A; ribosome c) mRNA; E; P; polymerase d) aminoacyl-tRNA; A; P; ribosome

d) aminoacyl-tRNA; A; P; ribosome

A major difference between eukaryotes and prokaryotes is that eukaryotes have a nucleus, whereas prokaryotes do not. Discuss the impact of having a nucleus on the creation of mature mRNA.

Answer: Because prokaryotes do not have a nucleus, the translational machinery is able to attach to the mRNA as it is being synthesized. Thus, there is no time to process the mRNA. In eukaryotes, the translational machinery is not present in the nucleus. Thus, there is time for the cell to process the mRNA before it is transported from the nucleus to the cytoplasm and translated into protein.

Two eukaryotic proteins were found to be very similar except for one domain that was very different. Which of the following processes is most likely to have contributed to this phenomenon? a) multiple random mutations within specific exons of the gene. b) differences in pre-mRNA splicing that results in an altered pattern of exon inclusion. c) differential acetylation of specific histone proteins prior to transcription. d) use of different transcriptional activators. e) All of the above.

b) differences in pre-mRNA splicing that results in an altered pattern of exon inclusion.

Which of the following statements is NOT true about enhancers? a) Enhancers contain sequences that are recognized by transcription factors. b) Enhancers can differ for each gene in a eukaryotic cell (although overlap is possible). c) Enhancers represent control elements located far away from the promoter. d) Enhancers are recognized by and bind directly to RNA polymerase. e) Enhancers can be located thousands of nucleotides upstream of downstream of the gene they affect.

What would Avery, Macleod, and McCarty have concluded if their results had been that only RNAse treatment of the heat-killed bacteria prevented transformation of genetic virulence? a) that DNAse or protease, but not RNase, stimulates transformation b) that DNA was the genetic material c) that RNA was the genetic material d) that protein was the genetic material

c) that RNA was the genetic material

How many primase molecules are needed on the leading strand? The lagging strand?

Leading = 1 Lagging = Multiple one for each Okazaki fragment.

Telomeres regulate the replication of the ends of chromosomes in eukaryotes. Why is this structure implicated in human aging?

Telomeres are structures at the ends of eukaryotic chromosomes that contain tandem DNA sequences added to the 3′ ends by the enzyme telomerase. Telomeres stabilize chromosomes by preventing the loss of genomic information after each round of DNA replication. Human somatic cells contain little or no telomerase, and those that do get progressively shorter and enter premature senescence. People with diseases of premature aging such as Werner syndrome and dyskeratosis congenital have shorter telomeres than healthy people.